Recently, an SR motor such as a motor for driving of an electric vehicle is known. When the SR motor is controlled, the SR motor is controlled so that a throttle opening degree based on an operating signal of an acceleration pedal is larger, and a target torque (an excitation current) is larger.
Conventionally, as shown in FIG. 16, the target torque is changed to a current instruction value I and an angle instruction value θ referring to a predetermined map MP when the target torque is given the SR motor 71 on a control of the SR motor 71. Hereupon, a battery voltage and motor rotational number are considered in a change (I and θ). The current instruction value I and the angle instruction value θ are given to a driving circuit 72, the SR motor 71 is controlled by these instruction values (I and θ).
However, if a control apparatus of the SR motor is an open loop, a torque fluctuation of the electric motor causes a resonance vibration for the SR motor or the vehicle body when a vehicle mounting on the SR motor has a resonance characteristic by an effect of a shaft, a twist of a tire, and a spring of a suspension, e.t.c. That is, as shown in FIGS. 18(a) and 18(b), when the target torque Req_trq suddenly changes by an operation of the accelerator pedal as shown in FIG. 18(b), the SR motor or the vehicle body vibrates by the torque fluctuation. The control apparatus has a stability characteristic reducing the vibration, when a step input of the vibration of the resonance frequency band happens during the torque fluctuation, a resonance phenomenon of which repeats the vibration many times. The vibration of the SR motor 71 caused by a resonance of the motor per se or a resonance of the vehicle body results in a rotational unevenness for a shaft of the SR motor 71. As the rotational unevenness gives little by little a load (a twist) to the shaft of the SR motor 71, there occurs a vibration for front and rear directions of the vehicle, which is unpleasant for crew of the vehicle.
To solve the abovementioned problem by a control of the microcomputer, a design of a high order controller is needed. If the abovementioned problem is solved by the design of the high order controller, the program becomes to complicate, the program cannot be stored in a predetermined program domain with restricted calculating time. On the other hand, when a low order controller is designed, it needs a coefficient to be set for each type of vehicle. Therefore, a lot of time is spent on a development for difference vehicles.